[Xen-devel] [PATCH 1/2] Revert "kexec/x86: do not map crash kernel area"

[David Vrabel <david.vrabel@xxxxxxxxxx>]

From: David Vrabel <david.vrabel@xxxxxxxxxx>

This reverts commit 7113a45451a9f656deeff070e47672043ed83664.

The kexec code uses map_domain_page() on pages within the crash
region, so this mapping is required if the crash region is within the
direct map area.

Wthout this revert, loading a crash kernel may cause a fatal page
fault when trying to zero the first control page allocated from the
crash area.  The fault will occur on non-debug builds of Xen when the
crash area is below 5 TiB (which will be most systems).

Reported-by: Don Slutz <dslutz@xxxxxxxxxxx>
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
 xen/arch/x86/setup.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 4833ca3..f07ee2b 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1097,7 +1097,9 @@ void __init __start_xen(unsigned long mbi_p)
                          mod[i].mod_start,
                          PFN_UP(mod[i].mod_end), PAGE_HYPERVISOR);
     }
-
+    map_pages_to_xen((unsigned long)__va(kexec_crash_area.start),
+                     kexec_crash_area.start >> PAGE_SHIFT,
+                     PFN_UP(kexec_crash_area.size), PAGE_HYPERVISOR);
     xen_virt_end = ((unsigned long)_end + (1UL << L2_PAGETABLE_SHIFT) - 1) &
                    ~((1UL << L2_PAGETABLE_SHIFT) - 1);
     destroy_xen_mappings(xen_virt_end, XEN_VIRT_START + BOOTSTRAP_MAP_BASE);
-- 
1.7.2.5


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